Sodium crystallises in bcc structure with radius $1 \cdot 86 \times 10^{-8} \mathrm{~cm}$. Calculate the…

Sodium crystallises in bcc structure with radius $1 \cdot 86 \times 10^{-8} \mathrm{~cm}$. Calculate the edge length of unit cell?
  1. $4.29 \times 10^{-8} \mathrm{~cm}$
  2. $6 \cdot 20 \times 10^{-8} \mathrm{~cm}$
  3. $8 \cdot 05 \times 10^{-8} \mathrm{~cm}$
  4. $3 \cdot 72 \times 10^{-8} \mathrm{~cm}$

Solution

For bcc unit cell, $r=\frac{\sqrt{3} a}{4}$ $\therefore \quad \mathrm{a}=\frac{4 \mathrm{r}}{\sqrt{3}}=\frac{4 \times 1.86 \times 10^{-8} \mathrm{~cm}}{1.732}=4.29 \times 10^{-8} \mathrm{~cm}$

Asked in: MHT CET 2020 (15 Oct Shift 1)

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